Printing Machine Safety System

ABSTRACT

A screen printing safety system is provided. The system includes a screen printing machine, and a plurality of zones in the vicinity of the screen printing machine. Each of the zones includes at least one sensor for sensing encroachment past a predetermined point. The sensors are adapted to stop operation of the screen printing machine when encroachment is sensed in at least one of the plurality of zones.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/056,425 filed Oct. 17, 2013, which claims the benefit of U.S.Provisional Application No. 61/715,072 filed Oct. 17, 2012, the contentsof which are incorporated herein by reference.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

N/A

TECHNICAL FIELD

The present invention generally relates to screen printing machines, andin particular to a safety system for use with such machines.

BACKGROUND OF THE INVENTION

Indicia applied permanently to articles of clothing and other textileshave become very popular. Fanciful indicia, such as logos, slogans,college names, sports team names and sayings, are now commonplace. As aresult, screen printing has become very popular. Large, commercialoperations screen printing textiles are common today.

Indicia can be one or more colors. Typically, a screen printing machinehas at least one station for each color employed. For example, a designincorporating two colors will have at least two printing stations, onefor each color. A design employing eight colors will have at least eightstations. Each station generally includes a printing head, whichsupports a single screen, the ink to be used at that particular stationand a mechanism for applying the ink to the textile. Each color iscarried by a single screen. The textile to be screened travels fromprinting station to printing station by one of a number of methods, suchas a chain or a rigid arm. The textile is usually carried by a metalpallet, pallet support, flat bed, or platen. Common printing machinesinclude turret, oval and linear type machines. In addition to printingstations, there may also be curing stations to heat and set the inksplaced on the textile or substrate.

In the screen printing process, a stencil screen is typically blocked(called “masked” in the industry) to embody the desired indicia and isthen placed over the item to be printed. Ink of one color is then addedto the screen surface and flooded onto the indicia by a flood bar ofconventional design. The ink may be of any type well-known in theindustry for screen printing. After the ink is flooded onto the screen,the ink is squeegeed through the screen interstices onto the item,leaving ink of the desired color where the interstices in the screen areunblocked. The squeegee can be of any type known in the art.

After the item is printed on, it is moved to a station where one or moreoperators transfer the article to a drying rack, conveyor surfaceleading to a dryer, or the like. This requires quick and deft handlingby the operator because the cycling of the printing machine may print ashirt every four to six seconds. Further, as the articles are typicallyadhered to the platen with an adhesive, the article must be lifted at anangle to break the adhesive seal without smudging the print on thearticle.

Unfortunately, operators, bystanders, and others are sometimes injuredwhile working with or near the machine when it is in operation. This issometimes caused by inattentiveness and/or failure to appreciate thepossible dangers associated with printing machines when they are beingoperated. The present invention provides a system that stops allprinting activities when a person is in an unauthorized zone, and indanger of potential harm.

SUMMARY OF THE INVENTION

A screen printing safety system is provided that is to be used for ovaland turret style printing machines. The system includes a plurality ofzones in the vicinity of the screen printing machine. Each of the zonesincludes at least one sensor for sensing encroachment past apredetermined point. The sensors are adapted to stop operation of thescreen printing machine when encroachment is sensed in at least one ofthe plurality of zones.

BRIEF DESCRIPTION OF THE DRAWINGS

To understand the present invention, it will now be described by way ofexample, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a screen printing safety system made inaccordance with the teachings of the present invention;

FIG. 2 is a perspective view of a first zone of the screen printingsafety system of FIG. 1;

FIG. 3 is a perspective view of a second zone of the screen printingsafety system of FIG. 1;

FIG. 4 is a further perspective view of the second zone of the screenprinting safety system of FIG. 1;

FIG. 5 is a still further perspective view of the second zone of thescreen printing safety system of FIG. 1 in operation;

FIG. 6 is a perspective view of a third zone of the screen printingsafety system of FIG. 1;

FIG. 7 is a further perspective view of the third zone of the screenprinting safety system of FIG. 1;

FIG. 8 is a still further perspective view of the third zone of thescreen printing safety system of FIG. 1;

FIG. 9 is a perspective view of a screen printing safety system made inaccordance with the teachings of the present invention;

FIG. 10 is a perspective view of a screen printing safety system made inaccordance with the teachings of the present invention;

FIG. 11 is a perspective view of a scanner and display in accordancewith the teachings of the present invention;

FIG. 12 is a perspective view of a scanner in accordance with theteachings of the present invention;

FIG. 13 is a perspective view of a scanner in accordance with theteachings of the present invention;

FIG. 14 is a perspective view of a display in accordance with theteachings of the present invention;

FIG. 15 is a perspective view of an air curtain in accordance with theteachings of the present invention; and

FIG. 16 is a perspective view of a screen printing safety system made inaccordance with the teachings of the present invention.

DETAILED DESCRIPTION

While this invention is susceptible of embodiments in many differentforms, there is shown in the drawings and will herein be described indetail preferred embodiments of the invention with the understandingthat the present disclosure is to be considered as an exemplification ofthe principles of the invention and is not intended to limit the broadaspect of the invention to the embodiments illustrated.

Referring to the FIGS., a screen printing safety system 10 is shown. Thesystem 10 includes a printing machine 12. The printing machine 12 can beany type of printing machine, including a turret, oval or linear typemachine having multiple stations. The system 10 also includes threezones: a first zone 14, a second zone 16, and a third zone 18.

The first zone 14 is located in an area where one or more machineoperators load and/or unload textiles or other printed materials onto oroff of the textile supporting pallets. The first zone 14 includes abarrier 20 (FIG. 2). The barrier 20 is located at a distance and in aposition in the vicinity of the machine 12 to ensure the safety of theoperators as they load and/or unload the textiles. The barrier 20preferably includes a gate 22. The gate 22 spans the operators' area andacts as a physical barrier to prevent an operator from approaching themachine 12 past a certain point or the line formed by the gate. Thedistance of the gate from the rotating pallets is such that it permitsan operator to reach over the gate and comfortably put the textile on astopped pallet or remove the textile from a stopped pallet. The gate 22is preferably about waist-high to prohibit an operator from physicallycrossing the gate 22, but to also allow the operator to reach over thegate 22 to load and/or unload textiles from the machine 12.

The second zone 16 includes a sensor incorporating a light curtain 24.The light curtain 24 spans the operators' position of the first zone 14,and begins at a height at about the top of the gate 22, approximatelywaist-high, and extends upward to a height of approximately six feetfrom ground level. The light curtain 24 preferably includes a lightproducing component or components 26 and a light reflecting component 27or components (FIGS. 3 and 4). The light curtain 24 permits an operatorto reach over the gate 22 when the arms or pallets of the printingmachine 12 are stopped during a print cycle to load and/or unloadtextiles. However, should the operator cross, encroach, or break thearea over or plane formed by the gate 22 while the machine 12 is inoperation and the arms or pallets are moving, the light curtain 24 willsense the crossing, encroachment, or break and stop the machine 12 fromrotating for the time when the light curtain 24 senses that the planeabove the gate 22 has been crossed. When the light curtain 24 sensesthat the encroachment has stopped, it restarts the machine 12.

Adjacent each side of the gate 22 is a fence 25 that supports the lightcurtain 24. One fence 25 supports adjacent the gate 22 the lightproducing component or components 26 and the other fence 25 supportsadjacent the gate 22 the light reflecting component 27, components orsensors. The fences 25 prevent one from physically reaching around orbypassing the gate 22 to unload or load a textile from the machine.Scanners 50 can also be used to define the boundaries of light curtain24 (FIGS. 11 and 12).

The third zone 18 includes a perimeter guard 28 (FIG. 6). The perimeterguard 28 establishes a safe perimeter 31 around the machine 12. Theperimeter guard 28 includes an encircling sensor or sensors having alight curtain 29 formed by a series of spaced apart light emittingcomponents 30, light receiving components 33 and light reflectingcomponents 32 located along the perimeter of the machine 12. Theperimeter guard 28 is located at a distance from the machine 12sufficient to ensure the safety of persons near the machine 12.

The embodiment shown uses four reflectors 32 to set up the third zone18. In another embodiment, for smaller printing machines 12, the thirdzone 18 can be constructed using three points. The light emittingcomponent 30 and light receiving component 33 can be located at onepoint, for example on or near the gate 22, and two reflectors 32 can beused with them to create the perimeter 28.

In another embodiment, a deflection mirror 60 can be used in conjunctionwith the light curtain 24 in the second zone 16. The deflection mirror60 can be placed in the center of the gate 22 to deflect light emittedby the light producing component 26 to the light receiving component 27.The light curtain 24, therefore, follows the contour of the gate 22.

In operation, the system 10 functions as follows. If an operator movesor opens the gate 22 of the first zone 14, or if the operator crossesthe light curtain 24 of the second zone 16, the light curtain 24 sensesthe movement or opening or crossing, and stops the machine 12.Additionally, if the perimeter guard 28 of the third zone 18 sensesthrough the light curtain 29 that the perimeter guard 28 has beencrossed, the machine 12 is stopped. The machine 12 restarts once theencroachment has ceased. The stopping of the machine 12 is accomplishedby a signal from the light curtains 24 or 29 to a controller (not shown)that acts like an emergency OFF switch. Once the signal from the lightcurtain 24 or 29 is no longer blocked, the controller signals themachine 12 to restart from the point where it stopped.

In an embodiment of the present invention shown in FIGS. 10 through 15,an electronic laser scanner 36 is mounted to the printing machine 12.The scanner 36 is preferably of the type manufactured by LeuzeElectronic GmbH+ Co., Model Rotoscan RS4-2E. The scanner 36 scans adesignated protective area. The scanner 36 can be programmed to create aprotective area of any desired size or shape. Preferably, the scanner 36is mounted such that it detects the presence of an object such as a handor other body part in the operator area or first zone 14 of the printingmachine. Additional scanners 36 can be situated to create the second andthird zones 16 and 18.

The scanner 36 can be programmed to have both a warning field 41 and aprotective field 43. For the warning field 41, the scanner 36 alerts avisual and/or audible warning when an object enters the area designatedas the warning field 41. For the protective field 43, the printingmachine 12 is instantly stopped should an object be detected entering orencroaching into the protective field 43. The controller of the printingmachine 12 can be programmed to have a delay of a desired time to allowan operator to enter the warning field 41 and/or the protective field 43for a desired amount of time before stopping the machine 12. This will,for instance, allow the operator to spray adhesive on platens 38, orplace or remove a substrate from the platens 38. The controller of theprinting machine 12 is programmed such that it starts up again after theobject has been removed from the protective field 43.

The scanner 36 can be associated with a display 39. As shown in FIG. 14,the display 39 can show the outlines of the warning field 41 and theprotective field 43. The outline 45 also shows objects within the rangeof the scanner 36 and their proximity to the fields 41 and 43.

It was found that when an operator sprayed glue onto the platens 38 ofthe printing machine 12 to adhere a substrate thereto, errant adhesivespray would interfere with operation of the scanner 36. An air curtainbar 40 mounted in front of the scanner 36 directs a curtain of airdownward from the scanner 36. The air curtain bar 40 is hollow andincludes a plurality of air openings 42 in the bottom thereof. The aircurtain bar 40 deflects errant spray and other airborne particles awayfrom the scanner 36.

While the specific embodiments have been illustrated and described,numerous modifications come to mind without significantly departing fromthe spirit of the invention, and the scope of protection is only limitedby the scope of the accompanying Claims.

1. A screen printing safety system comprising: a screen printingmachine; a plurality of zones in the vicinity of the screen printingmachine, each of the zones including at least one sensor for sensingencroachment past a predetermined point; the sensors adapted to stopoperation of the screen printing machine when encroachment is sensed inat least one of the plurality of zones.
 2. The screen printing safetysystem of claim 1 wherein the plurality of zones includes first, secondand third zones.
 3. The screen printing safety system of claim 2 whereinthe first zone includes a physical barrier.
 4. The screen printingsafety system of claim 3 wherein the physical barrier includes a gate.5. The screen printing safety system of claim 4 wherein the gate isapproximately waist-high.
 6. The screen printing safety system of claim2 wherein the second zone sensor includes a light curtain.
 7. The screenprinting safety system of claim 6 wherein the light curtain includes alight emitting component and a light reflecting component.
 8. The screenprinting safety system of claim 2 wherein the second zone is locatedabove the first zone.
 9. The screen printing safety system of claim 2wherein the third zone establishes a perimeter around the screenprinting machine.
 10. The screen printing safety system of claim 2wherein the third zone sensor includes a light curtain.
 11. The screenprinting safety system of claim 10 wherein the light curtain includes aplurality of light emitting components and light reflecting components.12. The screen printing safety system of claim 1 wherein the at leastone sensor includes a video comparison system.
 13. The screen printingsafety system of claim 1 wherein the at least one sensor includes aphotoelectric eye.
 14. The screen printing safety system of claim 1wherein the at least one sensor includes a scanner to scan a designatedarea for encroachment into a designated area.
 15. The screen printingsafety system of claim 14 wherein the designated area is the first zone.16. The screen printing safety system of claim 14 further including anair curtain, the air curtain directing airborne particles away from thescanner.
 17. The screen printing safety system of claim 14 wherein thedesignated area includes a warning field and a protective field.
 18. Thescreen printing safety system of claim 14 wherein there is a time delaybetween sensing encroachment into the designated area and stoppingoperation of the printing machine.
 19. The screen printing safety systemof claim 1 wherein the operation of the screen printing machine restartsonce the encroachment is no longer sensed.
 20. A screen printing safetysystem having two areas of protection from encroachment comprising: ascreen printing machine having a loading area and a printing area; afirst entryway to the loading area from outside the loading area havinga first vertical dimension from the floor to a top being sufficient toaccommodate a human operator; a segmented barrier to the first entrywayenclosing a first area of protection, the segmented barrier comprising:a gate moveable from an open position to provide access to a first zoneto a closed position to form a physical barrier to entry into the firstzone, the gate adapted to stop operation of the machine upon movement ofthe gate; and a first light curtain sensor for detecting encroachmentinto a second zone, the first zone and the second zone being disposed ina common vertical plane spanning a portion of the first entryway, thefirst zone extending approximately to the first height and the secondzone extending from a point upward therefrom to the top; a first fenceat one end of the gate to form a barrier to entry to the first area ofprotection; a second entryway to the printing area; a second lightcurtain sensor surrounding the second entryway to define a second areaof protection; and the first light curtain sensor and the second lightcurtain sensor being adapted to stop operation of the screen printingmachine when encroachment is sensed.
 21. The screen printing safetysystem of claim 20 further comprising a second fence at an opposed endof the gate to form a barrier to entry into the first area ofprotection.
 22. The screen printing system of claim 21 wherein the firstfence supports a light producing component of the first light curtainand the second fence supports a light receiving component of the firstlight curtain.